sporadic meteor

A meteor that occurs randomly, instead of
being associated with a meteor shower.
Sporadic meteors can be seen as "shooting stars" on any clear night, with
rates varying between 3–4 meteors per hour in the spring to 8–10
meteors per hour in the autumn. As well as this seasonal variation, there
is also a nightly variation – hourly rates being generally higher
just before dawn than they are in the late evening.